1. Field of the Invention
The present invention relates to a system and method for masking tinnitus. In particular, the present invention relates to a system and method for masking tinnitus using high frequency signals that affect the cortical auditory neurons in the brain.
2. Description of the Related Art
Tinnitus is defined as any ringing in the ears for which there is no external source. For example, a ringing, buzzing, whistling, or roaring sound may be heard as a result of tinnitus. Tinnitus can be continuous or intermittent, and in either case can be very irritating to one who has such an affliction.
Prior to the present invention, there has been no consistently effective way to counter, or mask, tinnitus. Most of the attempts to date have focused on masking the perceived sound. For example, U.S. Pat. No. 4,222,393, issued to Robert Hocks et al., describes a tinnitus masker that provides sounds in the range of from 1000 Hz to 5000 Hz, with a peak around 3000 or 4000 Hz. The patient is provided with sounds of varying pitch, one after another, so that the patient can identify the particular external sound having the same pitch as the tinnitus that the patient is experiencing. Once this is done, a power operated sound is applied to the ear of the patient, with that sound including a range of frequencies extending in a range above and below the perceived pitch.
U.S. Pat. No. 4,226,248, issued to Samir Manoli, describes a phonocephalographic device, which is used to passively, non-invasively monitor sounds from the surface and cavities of a patient""s head and correlate these sounds with a person""s electrocardiograph (ECG). A pair of insertable ear microphones of ample sensitivity are inserted into the patient""s ears, where they detect sounds from the surface and cavities of the head. These signals are processed, with the processing including the filtering of these signals through a frequency analyzer, which is made up of four Butterworth filters with a variable center frequency of between 150 Hz and 1000 Hz. In addition, the output signals may be passed to a oscillator for display on an oscilloscope, and or may be displayed on a chart recorder. As such, this apparatus may be used to diagnose certain medical problems of the patient, including tinnitus.
U.S. Pat. No. 4,759,070, issued to Barry Voroba et al., describes a patient controlled master hearing aid. The device includes a hearing test module and an operator""s and patient""s console. Based on this testing apparatus, the patient can select electronic components to be employed in his or her hearing aid, which can be configured to address tinnitus. Testing and selection of a tinnitus masker are performed using a pseudo-random generator, which is connected to circuits through an analog switch. U.S. Pat. No. 4,984,579, issued to Paul Burgert et al., describes a portable apparatus for treating afflictions of the ear. The apparatus temporarily changes the pressure in the ear canal to alleviate Meniere""s symptoms, such as hearing loss, vertigo, tinnitus, nausea, and aural fullness, in which the patient can facilitate immediate self-treatment.
U.S. Pat. No. 5,024,612, issued to van den Honert et al., describes an external ear canal pressure regulating device and tinnitus suppression device. This device uses an in-the-canal external ear pressure-regulating device to alter the pressure of the fluid within the external ear canal. The device includes an earplug with a bulbous portion, which contacts the wall of the external ear canal and creates a seal that seals the external ear canal interior from the ambient environment. The earplug is inserted into the ear canal, and the bulbous end is compressed. Fluid is passed outwardly into the ambient environment through a valve, creating negative pressure in the exterior ear canal, which pulls the eardrum out. This decreases the pressure in the inner ear space. Once the bulbous end is released, it re-expands. This process can be repeated until the desired pressure differential, or tinnitus relief, is achieved.
U.S. Pat. No. 5,167,236, issued to Franz Junker, describes a tinnitus masker having an electric circuit arranged in a housing and an earpiece which produces a sound spectrum that masks the tinnitus. The sound spectrum contains a line spectrum with a fundamental tone, with an adjustment range of the fundamental tone of from 0.125 kHz to 20 kHz.
U.S. Pat. No. 5,325,827, issued to Saren Westermann, describes a tinnitus masker which uses one or more signal generators, a controllable amplifier, one or two electroacoustic transducers for converting the electrical signals into acoustic signals, and a voltage source. The signal generators generate a continuously repeated, sinusoidal pure tone signal which slowly moves through the audio frequency range and whose cycle duration can be adjusted between 0.1 and 1000 seconds.
U.S. Pat. No. 5,403,262, issued to Timothy Gooch, describes a minimum energy tinnitus masker, which produces a masking signal with a selected center frequency, selected bandwidth, and selected volume. The bandwidth selector allows for four selections, xe2x85x9, xc2xd, 1 octave bandwidth, as well as broad bandwidth; and the center frequency selector is selectable in a range of between 500 and 16,000 Hz.
U.S. Pat. No. 5,628,330, issued to George Upham, describes an apparatus for treating people who are afflicted with tinnitus. This apparatus includes an inner metal shell that is fitted onto a patient""s head. The inner metal shell is nestled with a larger outer shell of similar characteristics. The patient experiences relief from tinnitus by holding an open end of the apparatus against the afflicted ear. The inventor of the ""330 patent believes that his apparatus may focus or somehow direct the xe2x80x9cnatural healing processxe2x80x9d of the human body to the injured part of the inner ear and/or direct external healing to the injured part of the inner ear. See column 4, lines 1-6.
U.S. Pat. No. 5,697,975, issued to Matthew Howard III, et al., describes a human cerebral cortex neural prosthetic for tinnitus. Howard""s device can be positioned in the brain so that electrical discharges can be accurately transmitted to geometrically dispersed locations in either a cortex or the thalamus, to allow a physician to physiologically test location and function of the neural prosthetic electrodes to reduce/eliminate the patient""s tinnitus. In this regard, Howard""s invention treats tinnitus in the brain, and not in the inner ear. In particular, Howard describes that the normal transduction of sound waves into electrical signals occurs in the cochlea, which is a part of the inner ear located within temporal bone. The cochlea is tonotopically organized, which means that different parts of the cochlea respond optimally to different tones. One end of the cochlea (base) responds best to high frequency tones, while the other end (apex) responds best to low frequency tones. The cochlea converts the tones to electrical signals, which are then received by the cochlear nucleus in the brain. This converted information is passed from the cochlea into the brain stem by way of electrical signals carried along the acoustic nerve, and in particular, the cranial nerve VIII. As the acoustic nerve leaves the temporal bone and enters the skull cavity, it penetrates the brain stem and relays coded signals to the cochlear nucleus, which is also tonotopically organized. Through many fiber-tract interconnections and relays, sound signals are analyzed at sites throughout the brain stem and the thalamus, with the final signal analysis site being the auditory cortex situated in the temporal lobe of the brain.
U.S. Pat. No. 5,663,727, issued to Peter Vokac, describes a frequency response analyzer and shaping apparatus, and digital hearing enhancement apparatus. The device provides many of the characteristics of a complete fast fourier transform suitable for audio signals and other signals. Vokac""s device customizes the frequency response for a particular patient, by providing an FFT""ed signal in an audible frequency range.
U.S. Pat. No. 5,692,056, issued to William Gardner, describes a method and apparatus for intracranial noise suppression. Vibrations from an instrument, as well as vibrations in the bone structure of the patient, are sensed and processed to generate canceling noise, which is then fed into the inner ear through vibrations on the head. Gardner""s device also includes an equalizer and an automatic adaptive coupler.
Also, there is on the market an electrical tinnitus suppressor called xe2x80x9cTheraband(trademark)xe2x80x9d. This is a battery powered headset that delivers amplitude modulated radio frequency waves to the subject. The carrier is about 60 kHz (possibly variable), with audio frequencies in the 200 Hz to 20,000 Hz range. The means of delivery is to the ear of the subject, where the sounds are received like any other sound. Theraband(trademark) uses electrical energy capacitively coupled to the head via electrodes on mastoid.
All of the above-mentioned tinnitus maskers do not appear to fully mask tinnitus, since they do not appreciate the true reason why tinnitus occurs. In particular, these conventional tinnitus maskers/suppressors operate under the assumption that the tinnitus problem is in the inner ear, and they attempt to provide a solution that is based on this assumption.
The invention is directed to a tinnitus masker, which includes an ultrasound source configured to output at least one ultrasound frequency. The masker also includes a vibration unit connected to the ultrasound source and configured to convert the ultrasound frequency to a vibration. The vibration unit is coupled to a person who experiences tinnitus, thereby providing a stimulation of the brain of that person, which in turn causes tinnitus masking.
The invention is also directed to a method of masking tinnitus, which includes a step of providing ultrasound noise to a head of a patient.
The invention is further directed to a method of examining a patient in order to provide an ultrasound treatment for that patient. The method includes a step of providing a plurality of ultrasound frequency tones, in sequence, to the patient, to determine an optimum ultrasound frequency for the patient. The method also includes a step of providing a plurality of audible frequencies modulated by the determined optimum ultrasound frequency, so as to determine a particular audible frequency that is optimum for the patient with respect to ultrasound tinnitus masking.